[Dimu]

@Dimu
I swore off rolling because it was draining my wallet and I've learn to sit back and enjoy what I have. I do not appreciate you shoving your tube rolling pics in my face.
Actually I pretty easy. I even find the stocks enjoyable.

I have stayed with Telefunken EL12 spez and Siemens E80CC since the last time I rolled them... Very musical and enjoyable, especially if volume is turned up.

Sadly I don't think I'll be doing much shopping for this amp- the market for interesting tubes has dried up. EL12 spez and E80CC are rare now and are up in price, usual GEC tubes are nowhere to be found. I wanted to try Tung Sol 6550 but I only found it for $700 a pair. I was thinking about trying EL156 but it has weak grid voltage rating like WE 350B- won't be sustainable in this amp. I am now thinking of building another amp with directly heated triodes. So instead of rolling tubes in one amp I can compare two amps to each other

Basically once I got the big power transformer into the case and improved mosfet cooling I don't want to touch the amp any more- it is just perfect. By the way with EL12 spez it runs much cooler than with TT-21 or 6550.

 

[vkung]

Why Mr. Fujita uses 12Au7 X 2 and 12AX7 X1 instead of 12AT7x 2 in TU-8600
1. To achieve higher stability of NFB, the overall NFB amount is decreased, and instead, cathode feedback is applied to 300B.
(This is why the third winding for cathode NFB is added to the OPT.)

2. Applying cathode NFB requires bigger driving amplitude for 300B.

3. To achieve such large driving amplitude, 12AU7 is more suitable than 12AT7, as its max. rating is higher than 12AU7.

4. Since the gain of 12AU7 is smaller than that of 12AT7, 12AX7 is used for the first stage.

Mr. Fujita conducted the circuit simulation to make sure his theory is correct, and confirmed that bigger amplitude can be achieved when 12AX7x1+12AU7x2 than 2x12AT7.
(The driving ability of 12AX7x1+12AU7x2 with TU-8600 circuit is 200V peak-peak without wave clipping)
For the headphone section, he uses 3 resistors tapped to the OPT. This made TU-8600 is a very good headphone amp..

 

[Hifi Boy]

I've been checking out some tubes for the new Elekit amp and it seems to me that these could be really good.

https://www.takatsuki-denki.co.jp/products/ta-300b.html

The price is double the KR Audio 300B, at least here in Japan!
Yet these are domestic tubes, while KR Audio is an import, incredible to say the least.

Also, I've recently auditioned the above mentioned Luxman p-750u and decided not to buy it. The sound was powerful, but on closer listen, it was just too cold for my tastes. I've also heard Fostex HP-V8, which btw uses 300B and KT88 tubes, but wasn't impressed either. Sounded flat and uninvolving to me.

Can't wait to hear the new Elekit. I'm almost 100% sure it's going to be amazing!

 

[Harry_Y]

Hello all, I just ordered a TU-8200 DX today, and read through the thread.

This will be going into my Home Office/Den so I would tend to believe it should work well for my use.

One of the things that did concern me a little prior to buying the amp is having parts that become unobtainable.
So it may be wise it get a few spares of the FETs and IC's in case they become obsolete and hard to find.

The ALPS Blue pot looks interesting (I'll need to find a source for that one).

Is there anything I should watch out for during the build?

Thank you

 

[Hifi Boy]

Hi Harry, welcome to the forum!

I'm no DIY expert and had my amp ordered already built, so I can't help you with that, but I wonder why you couldn't wait a bit longer for TU-8600 to come out and get it instead?

 

[Harry_Y]

Hi Harry, welcome to the forum!

I'm no DIY expert and had my amp ordered already built, so I can't help you with that, but I wonder why you couldn't wait a bit longer for TU-8600 to come out and get it instead?

I considered the 8600 but the 8200 will do what I need (audio for my Home Office/Den)

Plus the 8200

Is available today
Has the same output power (8 watts)
Is smaller in size (I want the amp on my desk so I can easily reach the volume knob, and my desk is already loaded with monitors etc)
Is a little less money (more money left over for playing with tubes)
Has Two Inputs (I did not want to buy a preamp or need to build a switch box)
Has an internal DAC available (Probably not the best quality but should work enough to run my PC through it if desired)

I've never dealt with Elekit, nor have I seen their products in person so this is a way for me to buy
in with a smaller investment and If I truly love their products... well there's always the living room.

 

[Hifi Boy]

Yeah, now that you listed all those readings, I have to say it makes sense!

What I can tell you, on the other hand, is that you won't regret ordering an Elekit product and certainly not from Victor. I ordered my Mundorf capacitors from him as well. Everything went very smoothly.

The TU-8200 is a one of a kind amp which sounds just amazing for its price point. I highly doubt you will get a better deal anywhere else for that money. Let us know what you think when the amp arrives!

 

[Hifi Boy]

Why Mr. Fujita uses 12Au7 X 2 and 12AX7 X1 instead of 12AT7x 2 in TU-8600
1. To achieve higher stability of NFB, the overall NFB amount is decreased, and instead, cathode feedback is applied to 300B.
(This is why the third winding for cathode NFB is added to the OPT.)

2. Applying cathode NFB requires bigger driving amplitude for 300B.

3. To achieve such large driving amplitude, 12AU7 is more suitable than 12AT7, as its max. rating is higher than 12AU7.

4. Since the gain of 12AU7 is smaller than that of 12AT7, 12AX7 is used for the first stage.

Mr. Fujita conducted the circuit simulation to make sure his theory is correct, and confirmed that bigger amplitude can be achieved when 12AX7x1+12AU7x2 than 2x12AT7.
(The driving ability of 12AX7x1+12AU7x2 with TU-8600 circuit is 200V peak-peak without wave clipping)
For the headphone section, he uses 3 resistors tapped to the OPT. This made TU-8600 is a very good headphone amp..

Hey Victor.

Seeing as how the Wall of Sound guys still haven't published the review of TU-8600, can you let us know how does the new amp compare with TU-8200?

With and without the upgrades of course!

 

[vkung]

TU-8600 is a 300B amp. The sound of 300B is different from 6L6 tube.
TU-8600 has a third winding (CFB to reduce the Negative Feedback..

(output transformer with cathode feedback CFB winding)
To make the most of the 300B tubes, the characteristics of the various parts and circuits including the OPT have been improved. NFB is applied to the cathode of the 300B by the third winding of the output transformer as well as to the voltage of the amplifying stage. Overall NFB is minimized as well as the chance for transient response.

Why CFB is important - Cathode Feedback minimizes THD and intermodulation distortions and makes total bandwidth ultra-wide without using overall negative feedback from output to input of your amp. All of it makes sound amazing, detailed and spacious..

you can use Lundahl LL2770 (custom made for TU-8600)

 

[Hifi Boy]

How much wider would you say the soundstage is compared to TU-8200?
What about the detail, sweetness and warmth of the sound?

I'm using KT-88 with my TU-8200, so how would you compare a TU-8200 with KT-88 and TU-8600 with 300B?

 

[vkung]

IT is quite different in sound .. TU-8600 with Lundahl is double the price of TU-8200. Also 300B is 3 times more than KT88.
Indeed, TU-8600 is very musical.. It is my personal preference.

 

[Hifi Boy]

Quite musical you say. That's good, I love warm, smooth and musical amps.
Unfortunately, I'll have to wait till November to hear it at this year's Fujiya-Avic show.

The thing is, I'm looking for an endgame amp and the TU-8200 value for money is beyond any amp I've ever heard, which is why I'm considering TU-8600 now.
As I've mentioned earlier, after auditioning the Luxman p-750u earlier, its now off the table because its too cold and uninvolving, I prefer my TU-8200 (87K yen assembled) to this 320K yen amp.

The other 2 amps I'm thinking about are Goldmund Telos HDA (9625 CHF) and Viva Egoista 2A3 (€7250).

Yes, they are way more expensive than even maxed out TU-8600 with all the upgrades you offer, but honestly, I would not be surprised if, when maxed out with all the upgrades and fitted with above mentioned Takatsuki 300B, this amp could probably match their sound. I'm actually only basing this on my experience with my TU-8200 and actually having heard Goldmund Telos HDA. Haven't yet heard the Egoista, but people say its the smoothest and sweetest sounding amp out there.

I'll have the opportunity to compare Goldmund again with TU-8600 at the Fujiya-Avic show this November, and then I'll make my decision.
I will certainly post my impressions when comparing the TU-8600 and the Goldmund. Then, people will have an idea how close/far they actually are with this Elekit set from what is currently considered the best all-in-one DAC/AMP out there.

 

[vkung]

The sound from solid state and Tube amp is quite different. AMtrans in Tokyo will offer upgrade version of TU-8600.

 

[Hifi Boy]

I remember I went there when I bought Mundorfs from you, because you recommended this shop to me, haha!

Yes, they did a good job of installing them into my Elekit, but I'm not sure whether they will have the Lundhals as well.

I'll try contacting them to see whether I can come for a listen before the Fujiya-Avic in November.

Thanks for reminding me about them Victor!

 

[vkung]

Yes Amtrans will carry Lundahl LL2770